Elastomers synthetic materials and latex

Elastomers include materials such as natural or synthetic rubber that are able to resume their original length after stretching. Rubber was the first such material used in furniture production but has been much replaced by synthetic materials. Synthetic loose fillings include spaghetti and chip cut foams, foam crumb, cut and curled nylon monofilament and polystyrene beads.

The ability of elastomers to be moulded was a real asset in the development of mass seating. In conventional upholstery the ability to match profiles of one seat to many others required very skilled, and therefore expensive, work. Preformed seating requires far less, and less skilled, labour but costs may still run high since the production of large runs of one type of seat are required to off-set the cost of mould production.

Sheet ('slab stock') and moulded materials

The selection of fillings is guided by factors such as price, comfort and durability that are in turn are influenced by density, resilience and ease of use. The production of upholstered furniture using synthetic or latex sheet or loose material still requires substantial manual labour. Various densities of the materials are cut, shaped and assembled (commonly with adhesives and staples) to form comfortable yet durable surfaces. For example, a shaped front edge of reconstituted crumb foam might be combined with a seat deck of firm sheet foam and a cushion of soft spaghetti cut foam. This is well illustrated in James (1990).

Foams Foams are available in sheets, of varying densities and qualities for handbuilding, made by one or other of the following methods.

Bonded chip foam or reconstituted foam is formed from off-cuts of foam crumbed and mixed into a new batch of foam to form a very high density mix for heavy use. The foam chip/crumb acts like gravel in a concrete mix or grog in a ceramic mix. Pre-shaped moulded forms are manufactured. Walls of high density chip foam may be used to enclose softer foams. The purpose of walling is to retain shape in the same way that a stitched or rolled edge would in conventional upholstery. Chip foam is difficult to cut thinly as it tends to break up.

Cavity foams are sheet materials containing moulded cavities. They come in a variety of depths but must be walled in with sheet material. They are often glued 'back to back' to create cushions.

Pincore foam is sheet material perforated with holes. Various thicknesses and densities are available. This material does not need to be walled in. In practice the sheet materials may be glued together, with adhesive applied by brush or spray, or textiles may be stuck to them for tacking to frames. Textiles may be used to encase the materials to protect them from exposure to light or handling.

Rubberized fillings are sheets of pre-carded loose filling which have been sprayed with latex milk and vulcanized. They may also be packed in moulds.

Needled fillings are sheets of pre-carded loose fillings which have been pushed into a textile ground by a machine containing barbed needles.

Sheet fibre such as cotton flock and polyester, are used as skimmer layers, second fillings and cushion filling. The material may be loose, bound, or come with a skin of adhesive, for example, polyester wadding with a skin of PVA adhesive.

Machine-made roll edges are tubes of textile containing loose jute fibre or paper fillings. Rolls are also available in moulded rubberized fill and chip foam.

THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.